Electronic musical instrument keyboard apparatus

Abstract

Keyboard apparatus includes: a plurality of white and black keys: a plurality of mass body units each pivotable in response to operation of a corresponding one of the keys; a frame having mounted thereon the plurality of keys and mass body units; and upper- and lower-limit stoppers provided on the frame for limiting a pivotable range of each of the mass body units by the mass body unit colliding against the stoppers. Each of the mass body units includes a cavity portion provided in a section thereof that pivots against a gravitational force as the corresponding key is depressed, and a plurality of particles are accommodated in the cavity portion with some vacant space left in the cavity portion.

1. An electronic musical instrument keyboard apparatus comprising:
 a plurality of keys: 
 a plurality of mass body units each pivotable in response to operation of a corresponding one of the keys; 
 a frame having mounted thereon said plurality of keys and said plurality of mass body units; and 
 movement limiting members provided on said frame for limiting a pivotable range of each of said mass body units by the mass body unit colliding against said movement limiting members, 
 wherein each of said mass body units includes a cavity portion provided in a section thereof that pivots against a gravitational force as the corresponding key is depressed, and 
 a plurality of particles are accommodated in said cavity portion with a vacant space left in said cavity portion. 
 
   
   
     2. The electronic musical instrument keyboard apparatus as claimed in  claim 1  wherein a shock absorbing member is provided within said cavity portion. 
   
   
     3. The electronic musical instrument keyboard apparatus as claimed in  claim 1  wherein each of the particles is coated with a soft material. 
   
   
     4. The electronic musical instrument keyboard apparatus as claimed in  claim 1  wherein each of said mass body units includes left and right side wall portions arranged in a key-arranged direction,
 said cavity portion is defined between the left and right side wall portions, and 
 at least one of left and right side wall portions has optical transparency. 
 
   
   
     5. The electronic musical instrument keyboard apparatus as claimed in  claim 4  wherein at least one of left and right side wall portions not only has the optical transparency but also has one or more scale marks.